165.合併兩個排序連結串列

將兩個排序連結串列合併為一個新的排序連結串列

樣例

樣例 1:
	輸入: list1 = null, list2 = 0->3->3->null
	輸出: 0->3->3->null


樣例2:
	輸入:  list1 =  1->3->8->11->15->null, list2 = 2->null
	輸出: 1->2->3->8->11->15->null

"""
Definition of ListNode
class ListNode(object):
    def __init__(self, val, next=None):
        self.val = val
        self.next = next
"""

class Solution:
    """
    @param l1: ListNode l1 is the head of the linked list
    @param l2: ListNode l2 is the head of the linked list
    @return: ListNode head of linked list
    
 
"""
    def mergeTwoLists(self, l1, l2):
        # write your code here
        #初始化一個新的連結串列，迴圈，比較l1.val 和 l2.val的大小。最後，如果那個連結串列沒有取完，則直接丟進來
        
        #初始化一個新的連結串列
        dummay = ListNode(0)
        tail = dummay
        
        while l1 and l2:
            if l1.val < l2.val:
                #每一個賦予一個新的節點
                tail.next 
 
= ListNode(l1.val)
                l1 = l1.next
            else:
                tail.next =  ListNode(l2.val)
                l2 = l2.next
            tail = tail.next
            
            
        #最後，如果還剩下l1,或者l2
        if l1:
            tail.next = l1 
        else:
            tail.next = l2 
        
        return dummay.next